1. Field of the Invention
The present invention relates to an improvement of a camera using a film cartridge having a cartridge chamber for loading a film cartridge, a cartridge chamber lid for closing/opening the cartridge chamber, and a locking means for switching a supply spool in the film cartridge between a position where rotation of the supply spool is inhibited and a position where rotation of the supply spool is allowed.
2. Related Background Art
A film cartridge having an indicator means for indicating the use state of a film in a film cartridge on a supply spool or a member interlocked therewith and a locking means displaceable between a position where rotation of the supply spool is inhibited and a position where rotation of the supply spool is allowed is already proposed by the present applicant in Japanese Patent Application No. 3-183948 or U.S. Ser. No. 834,640.
This film cartridge uses the same scheme used in a film cartridge of a new scheme proposed in U.S. Pat. No. 4,834,306 to be described below.
This film cartridge comprises a film passing slit, a film which has one end fixed to a supply spool and is wound around the supply spool, a press member, mounted to be coaxial with the supply spool and having a regulation portion for preventing radial spread of an outermost portion of the film, for substantially preventing the outermost portion of the film from being brought into contact with an inner wall of the film cartridge, a release portion for partially deforming the press member and continuously releasing the outermost portion of the film from radial regulation of the press member, and a guide portion for guiding a film portion released from the radial regulation to the film passing slit. The outermost portion of the film is set not to slip on the press member due to the spread of the outermost portion caused by loosening of the film upon rotation of the supply spool in the film feed direction. A driving force is applied in the film feed direction, thereby feeding the film from the film cartridge.
In the film cartridge of this scheme, the film can be fed out from the cartridge upon rotation of the supply spool in the cartridge even after the film is drawn into the film cartridge. Film exposure can be performed up to an intermediate frame, the film can be then rewound into the film cartridge, and the film can be fed again to perform film exposure for the remaining frames.
The film cartridge proposed by the present applicant will be described below. This film cartridge employs this system and will be described in detail below.
Referring to FIGS. 38 to 40, this film cartridge includes an outer cover 1, a film passing slit 1a, an indicator 1b for indicating the number of frames "S" to "36", a supply spool 2, splines 2a1 and 2a2 to be engaged with a camera fork (not shown), and an index portion 2b. The position of the index portion 2b which points a specific position of the indicator 1b indicates the number of frames used or frames unused.
In order to specify the positional relationship between the supply spool 2 and the index portion 2b, the splines 2a1 and 2a2 have different shapes.
The above film cartridge also includes a lock lever 3 mounted in the outer cover 1 to be pivotal about a shaft 3c, as shown in FIG. 40. A film 4 is wound around the supply spool 2, as shown in FIG. 39.
In the film cartridge, press members 5 and 6 are respectively mounted in grooves 2c and 2d of the supply spool 2. One end of a spring 7 is fixed to the outer cover 1, and the other end of the spring 7 is fixed to the lock lever 3. The spring 7 applies a clockwise biasing force to the lock lever 3.
Upon reception of the clockwise biasing force from the spring 7, a ratchet 3b of the lock lever 3 is engaged with one of V-grooves 2e of the supply spool 2, thereby preventing rotation of the spool 2. In a state wherein the film cartridge is not loaded in a camera (not shown), a projection 3a extends from a window 1c formed in the film cartridge, and rotation of the supply spool 2 is inhibited. However, when the film cartridge is loaded in the cartridge chamber of the camera (not shown), the projection 3a of the lock lever 3 is pushed inside the cartridge by the wall of the cartridge chamber. The lock lever 3 is rotated counterclockwise against the biasing force of the spring 7. As a result, the ratchet 3b is disengaged from the corresponding V-groove 2c, and the supply spool 2 is free to rotate. The supply spool 2 is rotated by the fork of the camera (not shown).
The present applicant proposes a camera using this film cartridge (FIGS. 38 to 40) in Japanese Patent Application No. 3-210398. A film exposed halfway is rewound into the film cartridge, and the film is fed again by the fork so that the supply spool is stopped at a position indicating the film use state of the film cartridge, such as a position indicating the number of frames used.
In this prior art, however, during unloading or ejection of the film cartridge from the cartridge chamber after the supply spool 2 is stopped at the position indicating the use state of the film 4 of the film cartridge, since the lock lever 3 is switched to a position where rotation of the supply spool 2 is inhibited, the supply spool 2 is accidentally rotated by an impact caused when a user holds the film cartridge before the lock lever 3 is switched to the rotation inhibition position or by an impact caused when the film cartridge is biased to be ejected or unloaded by an eject member. In this case, a wrong use state is indicated, resulting in inconvenience.
In an alternative camera, the fork engaged with the supply spool 2 to drive the spool 2 is kept engaged with the supply spool 2 at least until the lock lever 3 is switched to the position where rotation of the supply spool 2 is inhibited. When the rotatable fork or fork gear is arranged to be largely movable in the axial direction of the film cartridge, various problems are posed. For example, the overall structure is undesirably complicated or loses compactness. In addition, rotation and driving characteristics are degraded (due to large play of parts).
In a camera proposed by the present applicant in Japanese Patent Application No. 3-169086, a bevel gear is used to rotate a fork, a fork gear, a cartridge chamber lid, a film cartridge, and the like about the bevel gear to open the cartridge chamber lid. In synchronism with the opening operation of the cartridge chamber lid, the fork is retracted to a position not to engage with the supply spool. Upon retraction of the fork, when the film cartridge is rotated together with the cartridge lid about the bevel gear, the supply spool 2 of the film cartridge may be rotated by an impact or vibration.